(1) Field of the Invention
The invention relates to a brake disk for disk brakes, in particular of land vehicles, with a friction ring received by a support section formed by, for example, a portion of a wheel hub, wherein the support section has an out-of-round outer formation on which the friction ring is seated torsion-tight with a centric opening of complementary out-of-round inner formation.
(2) State of Prior Art
Such a brake disk is known from EP-B-0 642 632. Therein is proposed a wheel hub and such a brake disk configuration for a vehicle wheel, which comprises a hub section borne rotatably on an axle end by a bearing device, a brake disk support connected with the hub section, a brake disk rotatably fastened on the brake disk support and a disk-form support, which is fastened on the hub by a screw-type connection and to which a wheel rim can be screwed. The brake disk support is developed radially outside of the screw-type connection unitarily with the disk-form support, wherein the brake disk support does not have a circular outer formation on which a brake disk with an opening having a congruent inner formation is rotatably fastened. Thereby a wheel hub and brake disk configuration is to be provided in which a common screw-type or welding connection for the brake disk and the brake disk support can be avoided. The known configuration is in particular disadvantageous since high fabrication expenditures, high accuracy of fit in the region of the non-circular formations and an additional securement of the brake disk on the brake disk support against axial displacement must be provided.
It is the task of the present invention to propose a brake disk of the above described type in which, with simple means, a nonuniform heat distribution in the friction ring, and thus a distortion of the friction ring, so-called xe2x80x9ccanopying-outxe2x80x9d of the friction ring, at the temperatures occurring during braking and heat transfer onto the wheel bearing are avoided. With the invention, in particular, on the other hand, undesirable wear of the friction ring and stress fractures in the friction ring are to be avoided and, on the other hand, the shortening of the service life of the lubrication oil, present in the wheel bearing and/or bearing parts of synthetic material, are to be counteracted.
This task is essentially solved according to the invention in the case of a brake disk of the above described type by the friction ring, and preferable also the support section, comprising cast metal with the friction ring being cast onto the prefabricated support section.
It was found that the cast connection according to the invention between the friction ring and the support section, in particular if the latter also comprises cast metal, is ruptured upon first heating of the brake disk, and thus during the first braking process, such that the friction ring is separated from the support section. In this way a brake disk which, relative to the prior art is simple in structure and mounting, and in which, due to the separation gap generated between the friction disk and the support section, excessive stress, and thus stress fractures, in the friction ring, even at high braking power, for example in the field of trucks, are avoided. Moreover, due to the separation gap formed, heat flow from the friction ring to the support section, and thus the wheel bearing, is prevented.
With different constructions the support section can be formed, for example, by a pot-like hub section of the brake disk itself, a bearing hub on which a wheel flange can be fastened, or by a unitary wheel flange hub, wherein the last variant is especially cost-effective. In case the friction ring is changed, the wheel hub (possibly with the bearing) can also be exchanged, such that a new manufacturer""s warranty can be issued for the entire assembly. If the support section is formed by a unitary wheel flange hub, a separate wheel flange screw-type connection is omitted, with corresponding weight saving.
When using a brake disk with a separate pot-like hub section, the hub section can comprise, for example, a high-strength metal material and the friction ring a specific high-temperature disk material.
The out-of-round formation of the support section is formed according to a special inventive concept by ribs or protuberances, preferably force-framing, protuberances. The number of ribs or protuberances can be varied according to the technical requirements. Here, as well as in the case with a general out-of-round shape, no special fabrication precision is required since, due to the casting of the friction ring onto the out-of-round shape, for example in the form of ribs or protuberances, irregularities are per force compensated. Force-framing protuberances have the advantage that they extend on all sides into the opening margin of the friction ring, such that not only the reliable transmission of torques but also a securement against axial displacement of the friction ring on the support section is ensured.
In further development of the inventive concept, the support section in the region of the out-of-round formation can be equipped with holes or slits for air circulation. If the friction ring is structured such that it is solid, the holes or slits can be omitted.
Further goals, characteristics, advantages and application feasibilities of the present invention are evident in the following description of embodiment examples in conjunction with the drawing. All described and/or graphically represented characteristics, by themselves or in any combination form the subject matter of the invention, independently of their recapitulation in individual claims or their reference back.